小编coo*_*ool的帖子

写作有一些优势吗？

t = linspace(0,20,21)

过度

t = 0:1:20

？

我理解前者会产生一个矢量,就像第一个那样.
任何人都可以告诉我一些linspace有用的情况t = 0:1:20吗？

我想在matlab中绘制以下函数:
f(x,y) = sqrt(1-x^2-4y^2) ,(if (x^2+4*y^2) <=1 )

        =  0                  ,otherwise.

我在matlab中编写了以下代码:

  x=0:0.1:10;  
  y=0:0.1:10;
  z=x.^2+4*y.^2;
  if (z <=1)
   surf(x,y,z);

  else
   surf(x,y,0);
  end

但会显示以下错误:
surface: rows (Z) must be the same as length (Y) and columns (Z) must be the same as length (X)
如何避免此错误...

I can't understand this: when I write the following code I obtain this graph in matlab.

x = [0 1 2 3 4 5];
y = [0 1 0 1 0 1];
figure
plot(x,y);

I had just expected that only the points written in arrays x and y would be plotted ,but the graph shows lines also...
I can't understand why is it so... Please help where am I wrong

我无法理解为什么在以下代码中只显示按钮,为什么不显示标签和文本字段.

import javax.swing.*;
import java.awt.*;

class Invent extends JFrame
{
    public Invent(){
        JFrame c=new JFrame("trying");
        JLabel label1;
        JTextField txtfld1;
        JButton buttoncomp;  

        label1=new JLabel("Enter the path");
        txtfld1=new JTextField();
        buttoncomp=new JButton("Update");
        c.add(label1);
        c.add(txtfld1);
        c.add(buttoncomp);
        c. pack();
        c.setVisible(true);
    }

    public static void main(String[] args)
    {
        new Invent();                                                          
    }
}

请帮忙......